Capacitor discharge system with speed control sub-circuit

ABSTRACT

Disclosed herein is a capacitor discharge ignition system comprising a first electronic switch connected to a capacitor charged in response to engine rotation and operable to selectively discharge the capacitor to an ignition coil, means connected to the first switch for actuation thereof to discharge the capacitor to the ignition coil in response to rotation of the engine so as to cause engine ignition, a second switch connected to the capacitor and operable to selectively discharge the capacitor other than to the ignition coil, and means connected to the second switch for actuation thereof in response to rotation of the engine above a predetermined speed so as to render operation of the first switch ineffective to cause engine ignition.

United States Patent 1191 Wood 5] Feb. 4, 1975 [54] CAPACITOR DISCHARGE SYSTEM WITH 3,646,377 2/1972 Cavil 123/148 E SPEED CONTROL SUB-CIRCUIT B E o 1 [75] Inventor: Donald H. Wood, Gurnee, I11. g [73] Assignee: Outboard Marine Corporation, Primary Examiflercharles Myhre Waukegan, I. Assistant Exammer-Ronald B. Cox [22] F] d S t 13 1971 Attorney, Agent, or Firm-Michael, Best & Friedrich 1e ep [21] App]. No.: 179,768 ABSTRACT Disclosed herein is a capacitor discharge ignition system comprising a first electronic switch connected to [52] Cl 123/148 123/148 g a capacitor charged in response to engine rotation and [51] Int Cl I F02 U00 operable to selectively discharge the capacitor to an ['58] Fie'ld 5 102 ignition coil, means connected to the first switch for "123/146 5 A actuation thereof to discharge the capacitor to the ignition coil in response to rotation of the engine so as [56] R f C1 d to cause engine ignition, a second switch connected to e erelices l e the capacitor and operable to selectively discharge the UNITED STATES PATENTS capacitor other than to the ignition coil, and means 3,356,082 12/1967 Jukes 123/148 E connected to the second switch for actuation thereof 3,430,615 3/1969 Chav1s.. 123/148 E in response to rotation of the engine above a predeter- 3515109 6/1970 f 123/148 E mined speed so as to render operation of the first 5 switch ineffective to cause engine ignition. 316121023 10/1971 Sohner 1'23/148 E 4 Claims, 3 Drawing Figures PATENTED 419-75 3.863.616

- sum 10? 2 CAPACITOR DISCHARGE SYSTEM WITH SPEED CONTROL SUB-CIRCUIT BACKGROUND OF THE INVENTION The invention relates generally to internal combustion engine ignition systems and more particularly to capacitor discharge ignition systems including both battery powered and magneto powered systems. The invention also relates to arrangements for preventing ignition in the event of an engine over-speed condition.

Reference is hereby made to the Patis application Ser. No. 831,007 filed June 6, 1969 and entitled Engine Speed Limiter, which application is assigned to the assignee of this application and which application discloses a transistor operated arrangement for grounding an ignition trigger circuit in response to engine operation above a predetermined speed.

Reference is hereby also made to the Chavis-U.S. Pat. No. 3,430,615 issued Mar. 4, 1969, which discloses an arrangement for limiting engine speed in connection with a battery powered breaker operated ignition system.

SUMMARY OF THE INVENTION The invention provides a capacitor discharge ignition system including means operable, in the event of an engine over-speed condition, for dumping the capacitor prior to normal discharge to effect spark generation.

More specifically, the invention provides a capacitor discharge ignition circuit including an electronic trigger switch which is connected to a trigger coil and which, in response to a signal generated by the trigger coil, discharges the capacitor through an ignition coil. The circuit also includes an electronic speed control switch which is connected to a speed sensing coil and which, in response to the generation of a signal from the sensing coil occurring incident to an engine overspeed condition, serves to discharge the capacitor prior to the time of normal operation of the trigger switch, thereby preventing engine operation during the occurence of an engine 0ver-speed condition.

Also in accordance with the invention,- the trigger coil and the speed sensing coil are located relative to I each other and to a suitable rotating magnet such that an engine over-speed signal is generated prior in time to the generation of a trigger signal effecting normal engine ignition operation. Separate-magnets could be employed for each of the speed sensing coil and the trigger coil. In accordance with the preferred embodiment of the invention, both coils are actuated by a single magnet.

Also in accordance with the invention, the ignition circuit includes a speed control sub-circuit including the speed sensing coil and the speed control switch, together with a zener diode which is located between the speed sensing coil and the speed control switch and which serves to prevent application of the signal generated by the coil to the switch unless the signal is above a given potential and thereby generated in response to engine speed above a given rate.

One of the principle objects of the invention is the provision of a capacitor discharge ignition system which is rendered temporarily inoperative in response to attainment of engine speed above a predetermined rate.

Another of the principal objects of the invention is the provision of a capacitor discharge ignition circuit 2 i including separate trigger and engine speed sub-circuits connected to the capacitor and arranged such that'the engine speed controlled sub-circuit is effective prior to operation of the trigger sub-circuit.

Anotherof the principal objects of the invention is the provision of a capacitor discharge ignition system which is-rendered temporarily inoperative in the event of an engine over-speed condition and which is relatively economical to manufacture and which will provide reliable service over a long and useful life.

Other objects and advantages of the invention will become known by reference to the following description and accompanying drawings.

DRAWINGS;

FIG. 1 is a wiring diagram of an engine ignition system embodying various of the features of the invention. 4

FIG. 2 is a plan view in section ofa flywheel arrangement'embodying various of the features of the inven tion.

FIG. 3 is a sectional view of the flywheel of FIG. 2 i I taken along line 3-3 of FIG. 2.

Before explaining the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodimentsand of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

GENERAL DESCRIPTION pacitor charging means can be employed, in the disclosed construction, such means: comprises a charge coil 23 which is electrically connected to the capacitor 19 so as to effect capacitor charging in response to engine rotation. The circuit 17 also includes an ignition coil 27 including a secondary winding 29 connected to a spark plug 31 and a primary winding 33 connected with the secondary winding 29 to a common ground 37 and connected through an electronic switch means 39 to the capacitor 19. The electronic switch means 39 forms a part of the trigger sub-circuit 21 and is operable to effect discharge of the capacitor 19 to cause engine ignition operation in response to a signal applied thereto by an ignition trigger coil 41 which is also a part of the trigger sub-circuit 21, which is located relative to the path of travel of a rotary trigger magnet 45, and which is operable to generate a triggering signal in response to engine rotation. The circuit 17 also includes a speed control sub-circuit 43 including electronic switch means 47 responsive to engine speed for discharging the capacitor 19, after charging and prior to operation of the trigger sub-circuit 21, so as to thereby render ineffective operation of the switch means 39 to cause engine ignition in response to the generation of a signal by the trigger coil 41.

Still more particularly as shown schematically in FIG. 1, the capacitor 19 includes one plate 49 connected to ground 37 and a second plate 51 which is connected through a lead 53 to the anode 57 of a diode 59. In turn, the cathode 61 of the diode 59 is connected through a lead 63 to one end of the charge coil 23 which, at its other end, is connected to ground 37. The charge coil 23 is located relative to rotary charging magnet 67 so as to periodically provide a potential which is effective to charge the capacitor 19. If desired, as already indicated, the capacitor could be battery charged through any suitable arrangement.

In order to prevent overcharging of the capacitor 19, there is provided a zener diode 69 having a cathode 71 connected to ground 37 and an anode 73 connected through a lead 77 to the lead 63 and therefor to the cathode 61 of the diode 57. When the electrical charge built up on the capacitor 19 exceeds a predetermined limit, the zener diode 69 breaks down to limit further charging of the capacitor 19.

Connected by a lead 79 to the lead 53, and thereby to the capacitor 19 and to the diode 59, is an ignition switch 81 which, when opened, permits normal operation of the circuit 17 and which, when closed, connects the lead 79 to ground 37 so as to prevent charging of the capacitor 19.

The switch means 39 of the trigger sub-circuit 21 comprises an SCR having an anode 87, cathode 89 and gate 91. The anode 87 is connected by a lead 93 to the primary winding 33 of the ignition coil 27 and the cathode 89 is connected by a lead 97 to the plate 51 of the capacitor 19. The gate 91 is connected by a lead 99 and through a resistor 95 to one end of the trigger coil 41, while the other end of the ignition trigger coil 41 is connected by a lead 111 to the cathode 89. The ignition trigger coil is wound so that, in operation, after capacitor charging has occurred, engine rotation causes passage of the triggering magnet 45 past the ignition trigger coil 21 and consequent generation ofa signal of the proper polarity to cause the SCR 39 to become conductive and therefor to permit discharge or dumping of the capacitor 19 through the SCR 39 from the ignition coil 27 and the consequent generation of an ignition spark.

Also in accordance with the invention, the speed control sub-circuit 43 includes means for preventing effective discharge of the capacitor 19 to the ignition coil 27 in the event of an over-speed condition. While other arrangements are possible, in accordance with the invention, in the specifically disclosed embodiment, such means includes the switch means 47 which comprises an SCR having an anode 117, a cathode 119, and a gate 121. The anode 117 is connected by a lead 123 to the plate 49 of the capacitor 19 and the cathode 119 is connected through a lead 127 with a resistor 129 which, in turn, is connected through a lead 131 to the leads 79 and 53 and therefor to the capacitor plate 51.

The cathode 119 of the SCR 47 is connected by a lead 133 to one end of an engine over-speed sensor or trigger coil 135 which, in the disclosed construction, is located relative to the path of travel of the triggering magnet 45 and which is operable to generate a triggering signal in response to engine rotation. However, a magnet other than the triggering magnet 45 could be employed. The other end of the engine over-speed sensing coil 135 is connected through a lead 141 to the cathode 143 of a zener diode 147 which also includes an anode 149 connected through a lead 151 to the SCR gate 121.

Connected in parallel relation between the leads 133 and 141 are an adjustable resistor 153 and a capacitor 157 which regulates the phase relationship of the voltage and current from the engine speed sensor coil 135. The resistor 153 is factory set and is employed to calibrate the speed control sub-circuit 43 so that the zener diode 147 will break down in response to voltage ofthe proper polarity-generated in the sensor coil incident to engine operation at or above a predetermined speed. As will be apparent from the further description, the engine speed sensor coil 135 is wound in the direction such as to provide a signal of proper polarity to operate to turn on, or make conducting, the SCR 47 just prior to operation of the trigger sub-circuit 21.

In accordance with the invention, the charge coil 23, the ignition trigger coil 41, and the engine speed sensor coil 135 are actuated by engine rotation in timed sequence so that capacitor charging occurs first, followed by actuation of the engine over-speed sub-circuit 43 in response to generation by the engine speed sensor coil 135 of a suitable signal in the event of an over-speed condition, and followed by actuation of the ignition trigger sub-circuit 21 in response to generation by the trigger coil with of a signal capable of turning on the trigger circuit SCR 39. Thus, in accordance with the invention, means are provided for causing this sequential operation of the charge coil, and the engine speed sensor coil, and the ignition trigger coil.

While various other arrangements could be employed, in the construction disclosed in FIGS. 2 and 3 there is provided a flywheel 161 which includes, on one face thereof, an annular groove or recess 167 which is fixed to the crankshaft 163 of an internal combustion engine (not shown). Suitably mounted on the engine, as for instance, on the engine block and located in the annular recess 167 are the charge coil 23, the ignition trigger coil 41, and the engine speed sensor coil 135. More particularly as shown in FIG. 2 and wiht regard to the direction of engine flywheel rotation which is indicated by the arrow 169, i.e., counterclockwise in FIG. 2, the engine speed sensor coil 135 is mounted approximately 170 in advance of the ignition trigger coil 41.

Both the engine speed sensor coil 135 and the engine trigger coil 41 are arranged around respective coil cores 171 and 173 which extend to adjacent the path of pole shoes (not shown) mounted in relation to the trigger magnet which is in the form of an annular ceramic magnet ring including two geometrically supplementary segments or sections 177 and 179 which are slightly less than approximately 180 in arcuate length and which are oppositely magnetized and magnetically separated by a pair of diametrically opposed magnetic interfaces, voids or dead areas 181.

Thus, as illustrated in FIG. 2, flux reversal occurs in the engine speed sensor coil 135 in response to passage of one of the magnetic voids 181 at a time 10 prior to flux reversal in the ignition trigger coil in response to the passage of the other magnetic void 181. Such flux reversals cause generation of signals which are of alternate polarity and which are applied to the gates of the SCRs 39 and 47. As signal generation occurs in response to flux reversal, and as flux reversal occurs first in the engine speed sensor coil 135 as compared to the ignition trigger coil 41, if engine speed is in excess of the predetermined limit, a signal of sufficient magnitude will be generated by the speed sensing coil 135 so as to break down the zener diode 147 and cause the SCR to discharge or dump the capacitor 19 prior to the signal generated by the ignition trigger coil 41.

While other arrangements are possible, the FIGS. 2 and 3 arrangement includes two diametrically located charge coils 183 which are series additive connected 7 and therefor can be regarded together as the previously mentioned charge coil 23. The charge coils 183 are located in close proximity to the pole shoes of six equiangularly spaced alnico magnets 187 which are fixed on the flywheel 161 and which individually or together can be considered to correspond to the charge magnet 67 of FIG. 1. The charge coils 183 respectively include cores 189 which extend from a magnetically permeable core member 191 which is also provided, intermediate the cores 189, with two series of four equiangularly spaced cores 193, 195, 197, and 199 adapted to receive alternator windings which are not a part of the disclosed invention. It will be noted, however, that the cores 193 are located in relatively close proximity to the charge coil cores 189 and that the cores 195, 197, and 199 are located in relatively remote relation to the charge coil cores 189. Accordingly, the charge cores 189 and 193 constitute, in effect and in relation 'to the pole shoes associated with the magnets 187, a U- shaped armature, whereby a complete magnetic circuit is provided prior to flux reversal.

' As also shown in FIG. 2, the magnets 187 are located at 60 intervals and, in relation to the coil cores 189 and 193, are spaced and located so as to obtain capacitor charging prior to the effective time of flux reversal with respect to the engine speed sensor coil 135 and the ignition trigger coil 41. Thus, the arrangement shown in FIG. 2 provides the desired sequence of operation. It is noted that the electrical direction of the winding of the speed sensor coil 135 and the ignition trigger coil 41 is such that the flux reversals occurring at alternate 180 intervals are ineffective to generate signals which would turn on the respective SCRs 39 and 47,

If desired, the disclosed arrangement could be employed to produce sparks at 180 intervals by providing a second trigger switch SCR which is actuated by the generation of potential having a polarity reversed from that which operates the SCR 39 and which is connected to a second primary ignition coil and by providing a second speed control sub-circuit including an SCR which is actuated in response to the generation of a signal of the polarity opposite from that which iseffective to operate the SCR 47.

In summary, in operation, as the flywheel 161 rotates, the capacitor 19 is first charged by the charge coil 23. After the last occurrence of capacitor charging, if the engine is operating at a speed above a predetermined level, the engine speed sensor coil 135 will generate a signal which actuates the SCR 47 to dump the capacitor 19 through the resistor 129 and therefor to prevent subsequent effective operation of the SCR 39 to cause spark occurence. Ten degrees later, flux reversal will occur in the ignition trigger coil 41 to thereby generate a signal which is effective, in the event of nondumping by the speed control sub-circuit 43, to turn on the SCR 39 so as to afford discharge of the capacitor 19 through the ignition coil 27 and thereby to cause the generation of a spark.

Various of the features of the invention are set forth being operative in response to first magnet rotation to charge said capacitor, an ignition coil, a first electronic switch electrically connected to said capacitor for selectively discharging said capacitor to said ignition coil,

a second electronic switch electrically connected to said capacitor for selectively discharging said capacitor other than to said ignition coil and including a contol terminal, a voltage breakdown device connected to said control terminal and operable to permit conduction upon the application of potential above a given level, an annular magnet comprising a first segment having an arcuate extent ofless than 360 and an arcuate periphery of one polarity and a second segment having an arcuate extent slightly less than the difference between 360 and the arcuate extent of the first segment and an arcuate periphery of the other polarity, a trigger coil having a core extending radially from and located adjacent to the rotational path of said arcuate peripheries and electrically connected to said first switch, said trigger coil being operable in response to annular magnet rotation to generate a trigger pulse which actuates said first switch to discharge said capacitor to said ignition coil so as to cause engine ignition, and an overspeed control coil having a core extending radially from and located adjacent to the rotational path of said arcuate peripheries and electrically connected to said voltage breakdown device, said overspeed control coil being operable: in response to annular magnet rotation above a predetermined speed to generate a speed control pulse having a potential above said given level, said overspeed control coil core being located relative to said trigger coil core to generate said speed control pulse subsequent to charging of said capacitor and prior to generation of said trigger pulse, whereby to cause conduction of said breakdown device and operation of said second switch to discharge said capacitor other than to said ignition coil and render subsequent operation of said ignition trigger coil ineffective to cause engine operation.

, 2. A capacitor discharge ignition system in accordance with claim 1 wherein said first and second switch means each comprises a silicon controlled rectifier.

3. A capacitor discharge ignition system for an internal combustion engine comprising a capacitor, a first rotating magnet, a charge coil having a core located adjacent to the path of first magnet rotation and electrically connected to said capacitor, said charge coil being operable in response to first magnet rotation to charge said capacitor, an ignition coil, a first electronic switch electrically connected to said capacitor for selectively discharging said capacitor to said ignition coil, a second electronic switch electrically connected to said capacitor for selectively discharging said capacitor other than to said ignition coil and including a control terminal, a voltage breakdown device connected to said control terminal and operable to permit conduction upon the application of potential above a given level, an annular magnet comprising a first segment having an arcuate extent of about 180 and an arcuate periphery of one polarity and a second segment having an arcuate extent of about 180 and an arcuate periphery of the other polarity, a trigger coil having a core extending radially from and located adjacent to the rotational path of said arcuate peripheries and electrically connected to said first switch, said trigger coil being operable in response to annular magnet rotation to generate a pulse which actuates said first switch to discharge said capacitor to said ignition coil so as to cause engine ignition, and an over-speed control coil having a core extending radially from and located adjacent to the rotational path of said arcuate peripheries and, with respect to the direction of an annular magnet rotation, at an angular spacing of less than 180 in advance of said trigger coil core and electrically connected to said voltage breakdown device, said overspeed control coil being operable in response to annular magnet rotation above a predetermined speed to generate a pulse immediately in advance of said trigger pulse and after charging of said capacitor, and ofa potential above said given level so as to cause conduction of said breakdown device and operation of said second switch to discharge said capacitor other than to said ignition coil prior to operation of said trigger coil to discharge said capacitor to said ignition coil.

4. A capacitor discharge ignition system in accordance with claim 3 wherein said first and second switch means each comprises a silicon controlled rectifier. 

1. A capacitor discharge ignition system for an internal combustion engine comprising a capacitor, a first rotating magnet, a charge coil having a core located adjacent to the path of first magnet rotation and electrically connected to said capacitor, said charge coil being operative in response to first magnet rotation to charge said capacitor, an ignition coil, a first electronic switch electrically connected to said capacitor for selectively discharging said capacitor to said ignition coil, a second electronic switch electrically connected to said capacitor for selectively discharging said capacitor other than to said ignition coil and including a contol terminal, a voltage breakdown device connected to said control terminal and operable to permit conduction upon the application of potential above a given level, an annular magnet comprising a first segment having an arcuate extent of less than 360* and an arcuate periphery of one polarity and a second segment having an arcuate extent slightly less than the difference between 360* and the arcuate extent of the first segment and an arcuate periphery of the other polarity, a trigger coil having a core extending radially from and located adjacent to the rotational path of said arcuate peripheries and electrically connected to said first switch, said trigger coil being operable in response to annular magnet rotation to generate a trigger pulse which actuates said first switch to discharge said capacitor to said ignition coil so as to cause engine ignition, and an overspeed control coil having a core extending radially from and located adjacent to the rotational path of said arcuate peripheries and electrically connected to said voltage breakdown device, said overspeed control coil being operable in response to annular magnet rotation above a predetermined speed to generate a speed control pulse having a potential above said given level, said overspeed control coil core being located relative to said trigger coil core to generate said speed control pulse subsequent to charging of said capacitor and prior to generation of said trigger pulse, whereby to cause conduction of said breakdown device and operation of said second switch to discharge said capacitor other than to said ignition coil and render subsequent operation of said ignition trigger coil ineffective to cause engine operation.
 2. A capacitor discharge ignition system in accordance with claim 1 wherein said first and second switch means each comprises a silicon controlled rectifier.
 3. A capacitor discharge ignition system for an internal combustion engine comprising a capacitor, a first rotating magnet, a charge coil having a core located adjacent to the path of first magnet rotation and electrically connected to said capacitor, said charge coil being operable in response to first magnet rotation to charge said capacitor, an ignition coil, a first electronic switch electrically connected to said capacitor for selectively discharging said capacitor to said ignition coil, a second electronic switch electrically connected to said capacitor for selectively discharging said capacitor other than to said ignition coil and including a control terminal, a voltage breakdown device connected to said control terminal and operable to permit conduction upon the application of potential above a given level, an annular magnet comprising a first segment having an arcuate extent of about 180* and an arcuate periphery of one polarity and a second segment having an arcuate extent of about 180* and an arcuate periphery of the other polarity, a trigger coil having a core extending radially from and located adjacent to the rotational path of said arcuate peripheries and electrically connected to said first switch, said trigger coil being operable in response to annular magnet rotation to generate a pulse which actuates said first switch to discharge said capacitor to said ignition coil so as to cause engine ignition, and an over-speed control coil having a core extending radially from and located adjacent to the rotational path of said arcuate peripheries and, with respect to the direction of an annular magnet rotation, at an angular spacing of less than 180* in advance of said trigger coil core and electrically connected to said voltage breakdown device, said overspeed control coil being operable in response to annular magnet rotation above a predetermined speed to generate a pulse immediately in advance of said trigger pulse and after charging of said capacitor, and of a potential above said given level so as to cause conduction of said breakdown device and operation of said second switch to discharge said capacitor other than to said ignition coil prior to operation of said trigger coil to discharge said capacitor to said ignition coil.
 4. A capacitor discharge ignition system in accordance with claim 3 wherein said first and second switch means each comprises a silicon controlled rectifier. 